Varsity came out of the blocks with all guns blazing and Roslyn keeper Nathan Watt did well to tip over the bar a sizzling 40m drive by Alex Mason after only 12 minutes.
Mason did even better minutes later when he dived full length to head in a right-wing cross at the far post to put University 1-0 up.
However, Roslyn's experienced player-coach Terry Boylan encouraged his side back into an effective passing game and, just before half-time, Harley Rodecka acrobatically volleyed in the equaliser.
Varsity kept up its attacking mode in the second half.
Coach Bain explained: "We tried to defend last week against Tech, and got done, so despite being players short, due to Easter, we decided to push forward and attack."
Roslyn coach Boylan said Varsity would take points off other clubs if it kept up that sort of attacking mentality.
"At half-time we decided to keep our passing game going and see if we could break them down and gain advantage".
The Roslyn breakthrough occurred when striker Tom Connor finished off a flowing series of passes from the back and Sean Brand slid the final penetrating ball through for Connor to shoot Roslyn ahead.
Connor did it again 10 minutes later as he spun superbly on an early pass, then laced Roslyn into a 3-1 lead.
However, after a corner, Tom McFarlane hit a great shot into the top corner that narrowed the score to 3-2.
But Roslyn's experienced striker Brand raced through in the closing minutes to shoot Roslyn to a 4-2 win.
Time was also of the essence at the Caledonian Ground where Northern grabbed a 90th-minute winner to beat the Otago Youth team 2-1.
Coach Neil Mackenzie's young side competed well with Northern and, after a 0-0 half-time scoreline, the match could have gone either way.
But it was Northern that edged ahead when Jason Burgess made a strong challenge for a ball dropping vertically into the Otago goalmouth and the Northern substitute beat keeper Brad Smith to score.
Northern continued to enjoy more ball possession but the young Otago side kept up a furious workrate and made regular swift breaks led by Michael Still.
Still's energy eventually drew a rash tackle that earned a penalty and Aajay Cunningham levelled the scores at 1-1.
Few would have disagreed with a drawn result, but Northen hit the jackpot when Otago failed to clear a late corner and, as the ball sat up invitingly, Tim Smith smashed in the winner.
At Memorial Park, a Phil Kelly hat trick spearheaded Mosgiel's 4-1 win over Queenstown after Regan Coldicott opened the scoring and Dunedin Technical beat Grants Braes 3-0 at Ocean Grove.
Caversham regained its scoring touch with a 6-3 win over Green Island.
David Dugdale and Rob Deeley got two apiece.
The goal of the match was a terrific drive by Green Island striker Ryan Atherton.
